Calcium carbide furnace gas waste heat recovery system

Abstract

The utility model discloses a calcium carbide furnace gas waste heat recovery system which mainly comprises a calcium carbide furnace, a furnace gas pipeline, a first recovery device, a second recovery device and a third recovery device. Wherein the three stages of recovery devices are arranged in series and are sequentially connected through a furnace gas pipeline, calcium carbide furnace gas sequentially enters the recovery devices, each recovery device is provided with a heat exchange unit, the heat exchange units are mutually connected through heat exchange pipelines, and step-by-step recovery of heat in the furnace gas is effectively achieved. Compared with the prior art, the device has the advantages that heat in high-temperature furnace gas can be efficiently recovered and converted into superheated steam, the heat exchange cost is low, the heat energy recovery rate is high, and the utilization rate of calcium carbide production energy is remarkably increased.

Description

Technical Field

[0001] This utility model relates to a waste heat recovery technology, and more particularly to a waste heat recovery system for calcium carbide furnace gas, belonging to the field of calcium carbide production technology. Background Technology

[0002] Calcium carbide furnace gas is a byproduct of calcium carbide production. Calcium carbide is produced by heating the raw materials lime and coke to 1800-2300℃ using an electric arc, along with a large amount of carbon monoxide. The furnace gas coming out of the calcium carbide furnace can reach a temperature of 800-1000℃. The main component of the furnace gas is carbon monoxide. The existing technology used by enterprises mainly involves dust reduction and cooling before transporting it to downstream units for use as fuel or C1 feedstock. The heat in the furnace gas is not recovered and utilized, resulting in a large waste of thermal energy resources.

[0003] Patent CN 102706173A discloses a new process for utilizing waste heat from calcium carbide furnace gas. The method involves first subjecting the high-temperature furnace gas to dust suppression before it enters a heat exchange system. After heat exchange, the heat energy in the furnace gas is converted into 40-50°C hot water, which is used for heating and domestic use in winter and cooling in summer. However, because calcium carbide enterprises are high-energy-consuming enterprises with relatively remote locations, the cost of low-temperature heat energy transmission is high, resulting in low recovery efficiency and limited application scope for this portion of heat energy. Furthermore, the method's use of dust suppression followed by heat exchange leads to significant loss of high-temperature heat energy, resulting in a low heat recovery rate.

[0004] Patent CN 217785862U discloses a waste heat recovery system for calcium carbide furnace gas. The main method is to use molten salt or heat transfer oil as the heat exchange medium to recover the high-temperature heat from the extraction flue section of the calcium carbide furnace gas. Specifically, a heat exchange layer is set on the outer wall of the extraction flue, and heat exchange is carried out using the heat exchange medium. The high-temperature heat exchange medium is stored in a high-temperature storage tank and then transported to an evaporation system for secondary heat energy conversion via a transfer pump, and then converted into superheated steam. This method is relatively complex and only recovers the heat energy from the extraction flue section of the furnace gas, resulting in high heat exchange costs and low furnace gas heat energy recovery rate. Summary of the Invention

[0005] The purpose of this invention is to provide a waste heat recovery system for calcium carbide furnace gas. This system can recover heat from high-temperature furnace gas and convert the heat into superheated steam. It not only has low heat exchange costs but also high heat recovery rate, significantly improving the energy utilization rate of calcium carbide production.

[0006] To achieve the above objectives, this utility model provides the following technical solution:

[0007] A waste heat recovery system for calcium carbide furnace gas includes a calcium carbide furnace, a furnace gas pipeline, a first recovery device, a second recovery device, and a third recovery device. The calcium carbide furnace and the three recovery devices are connected in series and sequentially via the furnace gas pipeline. The upper part of the recovery device is provided with a furnace gas inlet, and the top of the recovery device is provided with a furnace gas outlet.

[0008] Furthermore, each of the recovery devices is equipped with a heat exchange unit, namely a first heat exchange unit, a second heat exchange unit, and a third heat exchange unit. The bottom of the heat exchange unit is provided with an inlet, and the top of the heat exchange unit is provided with an outlet. The heat exchange units are connected to each other through heat exchange pipelines.

[0009] Furthermore, the recycling device consists of a cylinder and a cone, with the cylinder located above the cone and the bottom surface of the cone being sealed to one end of the cylinder.

[0010] Furthermore, the heat exchange unit is disposed within the cylinder of the recovery device, and the height of the heat exchange unit is less than the height of the cylinder.

[0011] Furthermore, the heat exchange unit includes two parallel annular pipes and several vertical pipes located between the two annular pipes. The annular pipes and vertical pipes are interconnected, and heat exchange medium flows inside the pipes. The inlet and outlet of the heat exchange unit are located on the two annular pipes.

[0012] Furthermore, the outlet end of the furnace gas pipeline extends into the interior of the recovery device, and the outlet of the furnace gas pipeline is located below the heat exchange unit, which increases the residence time of the calcium carbide furnace gas in the recovery device, allowing the calcium carbide furnace gas and the heat exchange unit to exchange heat fully and effectively recover the heat in the furnace gas.

[0013] Furthermore, a steam-water separation device is provided on the heat exchange pipeline between the outlet of the third heat exchange unit and the inlet of the second heat exchange unit. A heat exchange pipeline is provided between the top of the steam-water separation device and the inlet of the first heat exchange unit. A heat exchange pipeline is provided between the outlet of the second heat exchange unit and the steam-water separation device. A liquid level detection device is provided on the steam-water separation device.

[0014] Furthermore, the top of the cone is provided with a dust discharge port for discharging dust particles deposited on the cone portion.

[0015] Furthermore, the waste heat recovery system is also equipped with a circulating water tank, which is connected to the third heat exchange unit through a heat exchange pipeline. A booster pump is installed on the heat exchange pipeline to facilitate the flow of the heat exchange medium and heat exchange. The heat exchange medium can be any one of water, steam or heat transfer oil.

[0016] Furthermore, a heat exchange pipeline is provided between the circulating water tank and the second heat exchange unit, and a water replenishment valve is provided on the heat exchange pipeline. When the liquid level in the steam-water separator is too low to meet the heat exchange requirements, the water replenishment valve is opened to replenish the heat exchange medium to the second heat exchange unit in a timely manner.

[0017] Furthermore, the furnace gas outlet pipeline of the third recovery device is equipped with a temperature detection device to detect the temperature of the calcium carbide furnace gas in real time, and the flow rate and speed of the heat exchange medium can be adjusted according to the temperature of the calcium carbide furnace gas.

[0018] Compared with existing technologies, this invention can not only efficiently and fully recover heat from calcium carbide furnace gas and maximize energy utilization, but also has a lower cost in the heat exchange process. This technology effectively solves the long-standing problem of low high-temperature heat recovery rate in calcium carbide furnace gas and greatly improves energy utilization efficiency. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the structure of this utility model.

[0020] Figure 2 This is a top view of the third recycling device in this utility model.

[0021] Figure 3 This is an elevation view of the third recycling device in this utility model.

[0022] In the diagram: 1 is the calcium carbide furnace, 2 is the furnace gas pipeline, 3 is the ash discharge valve, 4 is the first recovery device, 5 is the first heat exchange unit, 6 is the heat exchange pipeline, 7 is the second recovery device, 8 is the second heat exchange unit, 9 is the water supply valve, 10 is the third recovery device, 11 is the booster pump, 12 is the circulating water tank, 13 is the third heat exchange unit, 14 is the temperature detection device, 15 is the steam-water separation device, 16 is the liquid level detection device, 17 is the annular pipe, and 18 is the vertical pipe. Detailed Implementation

[0023] The preferred embodiments of this utility model are described in detail below.

[0024] Example 1: This utility model provides a waste heat recovery system for calcium carbide furnace gas, which mainly includes a calcium carbide furnace 1 and three waste heat recovery devices, namely a first recovery device 4, a second recovery device 7, and a third recovery device 10. The calcium carbide furnace 1 and the three recovery devices are connected in series through a furnace gas pipeline 2. Each recovery device adopts a combination structure of a cylinder and a cone. The cylinder is located above the cone, and the bottom surface of the cone is sealed to the bottom surface of one end of the cylinder. The top of the cone is provided with an ash discharge port, and an ash discharge valve 3 is installed at the ash discharge port to discharge the dust accumulated in the inner cavity of the recovery device.

[0025] Each recovery device is equipped with an outlet and an inlet. The furnace gas inlet is located on the upper part of the side wall of the cylindrical body of the recovery device, and the furnace gas outlet is located at the top center of the cylindrical body of the recovery device. The furnace gas pipeline 2 passes through the outlet and extends vertically into the inner cavity of the recovery device. The length of the furnace gas pipeline 2 is greater than the height of the cylindrical body of the recovery device. Its main function is to increase the residence time of the furnace gas in each recovery device.

[0026] Each recovery device is equipped with a heat exchange unit, namely a first heat exchange unit 5, a second heat exchange unit 8, and a third heat exchange unit 13. Each heat exchange unit has an inlet at its bottom and an outlet at its top. The heat exchange units are connected by heat exchange pipelines 6. The heat exchange medium enters through the inlet at the bottom of the heat exchange unit via the heat exchange pipelines 6, flows from bottom to top within the unit, exchanges heat with the calcium carbide furnace gas outside the unit, and then flows out from the top outlet through the heat exchange pipelines 6 into the next stage heat exchange unit. The height of each heat exchange unit is less than the height of the cylinder of the recovery device.

[0027] The following is combined with Figure 1-3 The system described in this utility model will be further described in detail.

[0028] The high-temperature furnace gas generated by the calcium carbide furnace 1 is transported to the first recovery device 4 through the furnace gas pipeline 2, where it undergoes sufficient heat exchange with the first heat exchange unit 5 installed inside the first recovery device 4. After heat exchange, the furnace gas is transported to the second recovery device 7 through the furnace gas pipeline 2, where it undergoes sufficient heat exchange with the second heat exchange unit 8 installed inside the second recovery device 7. After the second heat exchange, the furnace gas is transported to the third recovery device 10 through the furnace gas pipeline 2, where it undergoes sufficient heat exchange with the third heat exchange unit 13 installed inside the third recovery device 10. After three stages of heat exchange, the temperature of the calcium carbide furnace gas is controlled at 240-270℃.

[0029] The heat exchange unit mainly includes two parallel annular pipes 17 and several vertical pipes 18 located between the two annular pipes 17. The annular pipes 17 and the vertical pipes 18 are interconnected, and the heat exchange medium flows inside the pipes. The inlet of the heat exchange unit is located on the bottom annular pipe 17, and the outlet is located on the top annular pipe 17. The vertical pipes 18 are of equal length and are arranged in parallel. The spacing between the vertical pipes 18 is equal. The cross-sectional area of ​​the annular pipe 17 is larger than the cross-sectional area of ​​the vertical pipes 18.

[0030] A steam-water separator 15 is installed on the heat exchange pipeline 6 between the outlet of the third heat exchange unit 13 and the inlet of the second heat exchange unit 8. The steam-water separator 15 has an outlet at both the top and bottom. The top outlet of the steam-water separator 15 is connected to the inlet of the first heat exchange unit 5 through the heat exchange pipeline 6, and the bottom outlet of the steam-water separator 15 is connected to the inlet of the second heat exchange unit 8 through the heat exchange pipeline 6. The steam-water separator 15 has two inlets on one side. One inlet is connected to the outlet of the third heat exchange unit 13 through the heat exchange pipeline 6, and the other inlet is connected to the outlet of the second heat exchange unit 8 through the heat exchange pipeline 6. The steam-water separator 15 is equipped with a liquid level detection device 16 for detecting the liquid level of the steam-water separator 15.

[0031] Preferably, the heat exchange medium of the heat exchange unit is circulating water, which is supplied by the circulating water tank 12. A booster pump 11 is installed on the heat exchange pipeline 6. After the booster pump 11 is started, the circulating water enters the third heat exchange unit 13 located in the inner cavity of the third recovery device 10 through the heat exchange pipeline 6, where it exchanges heat with the calcium carbide furnace gas in the third recovery device 10. The circulating water that has completed the heat exchange is output from the third heat exchange unit 13 and enters the steam-liquid separator 15. After the gas-liquid separation is completed in the separation chamber of the steam-liquid separator 15, the circulating water enters the second recovery device 7 again through the heat exchange pipeline 6. The second heat exchange unit 8 installed in the inner cavity exchanges heat with the furnace gas in the second recovery device 7 again. After the heat exchange is completed, the circulating water is output from the second heat exchange unit 8 and enters the steam-water separator 15. After separation in the separation chamber of the steam-water separator 15, the circulating water undergoes another heat exchange. The steam located at the top of the steam-water separator 15 is transported through the top outlet heat exchange pipeline 6 into the first heat exchange unit 5 installed in the inner cavity of the first recovery device 4. It exchanges heat with the high-temperature furnace gas in the inner cavity of the first recovery unit to convert the low-temperature steam into high-temperature steam, which is then transported to the next stage for use.

[0032] The steam-water separation device 15 is equipped with a liquid level detection device 16. The liquid level detection device 16 is interlocked with the water supply valve 9. When the liquid level in the steam-water separation device 15 is lower than the set value, the control valve automatically opens to replenish circulating water to the second heat exchange unit 8 in the inner cavity of the second recovery device 7. When the liquid level in the steam-water separation device 15 reaches the set value, the control valve automatically closes to stop water supply.

[0033] A temperature detection device 14 is installed on the outlet pipeline of the third recovery device 10. It is mainly used to detect the temperature of the calcium carbide furnace gas. The temperature detection device 14 is interlocked with the booster pump 11. When the temperature detection device 14 detects that the furnace gas temperature is high, the booster pump 11 automatically adjusts its operating frequency and increases the circulating water volume to quickly reduce the furnace gas temperature to meet the process requirements between 240-270℃. Conversely, the frequency of the booster pump 11 is reduced and the circulating water volume is decreased to keep the furnace gas temperature stably controlled between 240-270℃.

[0034] The high-temperature furnace gas contains a large amount of dust. During the heat exchange process, some particles will be deposited at the bottom conical part of the first recovery device 4, the second recovery device 7, and the third recovery device 10 due to gravity. The deposited particles are discharged through the ash discharge valve 3 set at the ash discharge port at the top of the conical part.

[0035] The above description is only a preferred embodiment of the present utility model. It should be noted that for those skilled in the art, several changes and improvements can be made without departing from the inventive concept of the present utility model, and these all fall within the protection scope of the present utility model.

Claims

1. A waste heat recovery system for calcium carbide furnace gas, comprising a calcium carbide furnace and furnace gas pipelines, characterized in that, The furnace is equipped with a first recovery device, a second recovery device and a third recovery device. The calcium carbide furnace is connected in series with the three recovery devices and is connected in sequence through furnace gas pipelines. The upper part of the recovery device is provided with a furnace gas inlet and the top of the recovery device is provided with a furnace gas outlet. Each of the recovery devices is equipped with a heat exchange unit, namely a first heat exchange unit, a second heat exchange unit, and a third heat exchange unit. The bottom of the heat exchange unit is provided with an inlet, and the top of the heat exchange unit is provided with an outlet. The heat exchange units are connected to each other through heat exchange pipelines.

2. The waste heat recovery system for calcium carbide furnace gas as described in claim 1, characterized in that: The recycling device consists of a cylinder and a cone, with the cylinder located above the cone and the bottom surface of the cone being sealed to one end of the cylinder.

3. The waste heat recovery system for calcium carbide furnace gas as described in claim 1, characterized in that: The heat exchange unit is housed within the cylinder of the recovery device, and the height of the heat exchange unit is less than the height of the cylinder.

4. The waste heat recovery system for calcium carbide furnace gas as described in claim 1, characterized in that: The heat exchange unit includes two parallel annular pipes and several vertical pipes located between the two annular pipes. The annular pipes and vertical pipes are interconnected, and heat exchange medium flows inside the pipes. The inlet and outlet of the heat exchange unit are located on the two annular pipes.

5. The waste heat recovery system for calcium carbide furnace gas as described in claim 1, characterized in that: The outlet end of the furnace gas pipeline extends into the interior of the recovery device, and the outlet of the furnace gas pipeline is located below the heat exchange unit.

6. The waste heat recovery system for calcium carbide furnace gas as described in claim 1, characterized in that: A steam-water separation device is installed on the heat exchange pipeline between the outlet of the third heat exchange unit and the inlet of the second heat exchange unit. A heat exchange pipeline is provided between the top of the steam-water separation device and the inlet of the first heat exchange unit. A heat exchange pipeline is provided between the outlet of the second heat exchange unit and the steam-water separation device. A liquid level detection device is installed on the steam-water separation device.

7. The waste heat recovery system for calcium carbide furnace gas as described in claim 2, characterized in that: The cone is provided with an ash discharge port at its top.

8. The waste heat recovery system for calcium carbide furnace gas as described in claim 1, characterized in that: It also includes a circulating water tank, which is connected to the third heat exchange unit via a heat exchange pipe, and a booster pump is installed on the heat exchange pipe.

9. The waste heat recovery system for calcium carbide furnace gas as described in claim 8, characterized in that: A heat exchange pipeline is provided between the circulating water tank and the second heat exchange unit, and a water supply valve is provided on the heat exchange pipeline.

10. The waste heat recovery system for calcium carbide furnace gas as described in claim 1, characterized in that: A temperature detection device is installed on the furnace gas outlet pipeline of the third recovery unit.

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